Dog Skin & Coat Disorders

posted: 05/15/12

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Skin and haircoat diseases in dogs can cause hair loss, scratching, and excessive licking, and can be the result of many disease processes. Learn more about the symptoms, diagnosis, and treatment of these diseases.

Dandruff

Many puppies seem to have more dandruff or dry, flaky skin than would be expected. This is quite normal in puppies and is especially noted in those with dark coat colors. This is simply because the dander becomes quite visible against the dark hair. In most puppies, especially those less than four months of age, the normal lubricating glands (sebaceous glands) of the skin tend to be underactive. As these glands mature their lubrication output increases to match the needs of the coat. Factors such as dry air (low humidity) will also contribute to dander production. Dander is dry, dead skin that in the absence of moisture will flake away and be visible as white flakes. This 'flaking' may also be itchy.

The only symptoms are the white skin flakes most pronounced about the neck, back and rump areas. The flaking process may create a mild itching much like humans experience from dry, flaky skin. There are no real risks other than hair loss. This, however, is rare. Severe flakiness or hair loss should not be considered normal dandruff production and an examination of the skin should be done. If the itching is intense, suspect other factors such as fleas, lice or mange mites. Fatty acid supplements such as Drs. Foster & Smith Vitacaps or Vitacoat work well at supplying needed oils for the hair coat. Oatmeal shampoos followed by a moisturizing rinse will help keep the oils in, cleanse the skin and remove the dander.

Acanthosis nigricans is a condition in which there is abnormal darkening of the skin. It is primarily a disease of dogs and has several different forms and causes. The disease can be divided into a primary form that is a genetic condition found primarily in dachshunds, and a secondary form that has several causes and can be found in any breed or age of dog. In the secondary form there is a mobilization of the pigment called 'melanin' to areas of chronic inflammation. It is the melanin that creates the dark appearance of the skin.

Primary acanthosis nigricans

The primary form of the disease occurs in dogs less than one year of age. In this form the skin darkens and thickens, seborrhea develops, and secondary infections with bacteria or yeast can occur. It can affect large areas of the body.

Primary acanthosis nigricans is not treatable but the condition can be controlled with steroids, melatonin injections, and frequent anti-seborrheic shampoos. This condition is rare and is diagnosed mainly through breed history and biopsy.

Secondary acanthosis nigricans

The secondary form of the disease is much more common. The darkening of the skin occurs because of one of three underlying conditions. 1) Friction caused by obesity or conformational abnormalities. 2) Endocrine imbalances including hyperthyroidism, Cushing's disease, or sex hormone imbalances. 3) Hypersensitivities due to food, inhalant (atopy), or contact allergies.

In addition to blackening of the skin, secondary acanthosis nigricans is often associated with chronic hair loss and/or itching and other skin problems. If an owner sees these skin conditions developing she should have the dog examined by a veterinarian and the underlying cause of the condition should be identified.

The treatment for secondary acanthosis nigricans usually consists of treating the underlying condition, e.g., through weight loss, thyroid medication or allergy relief. In more severe cases steroid therapy at low doses has helped to reduce inflammation in the skin. In addition vitamin E supplementation has shown to help in the recovery of some cases. The majority of time the condition will improve once the underlying condition has been identified and properly treated.

This condition is seen in dogs that possess a coat of two or three colors. This condition is inherited and can be seen in any dog, crossed or purebred with the above coloration. Bassett Hounds, Papillons and Schipperkes, among others, have been noted. The result is hair loss in the pigmented black or dark-haired areas of the young puppy. The hair loss progresses until the colored spots become bald. There is no treatment for this inherited condition.

Collie Nose (Nasal Solar Dermatitis)

'Collie nose' is used to describe a condition in which breeds with little or no pigment on their face develop lesions, usually on the nose, eyelids and lips. The lesions are caused by a hypersensitivity to sunlight. Despite the term 'Collie nose', breeds other than Collies can also be affected, especially Shetland Sheepdogs. Collie nose has an inherited component and is worse in areas with sunny climates.

What are the symptoms?

Usually the lesions appear as pink, raw areas about the nose and occasionally on the eyelids. The hypersensitive areas may actually ulcerate and develop a crusty scab-like covering. The condition may vary from mild irritation to severe ulcerating lesions that hemorrhage.

What are the risks?

Left untreated, severe discomfort can result. As the nasal tissues become deeply irritated, they may crack, bleed and impair breathing. All cases should begin treatment in the early stages. Advanced stages may develop into a form of cancer which can be deadly.

What is the management?

Before treatment can begin, this condition must be differentiated from various autoimmune disorders such as lupus erythematosus or skin cancer, which may cause similar lesions. Biopsies are usually warranted to help confirm the diagnosis.

Collie nose can be managed several ways. Exposure to sunlight should be kept to a minimum. Sunscreen lotions help, but have limited effectiveness due to a dog's licking behavior. In some cases the treatment of choice is tattooing. A permanent black ink is tattooed into the affected areas. The black ink serves as a shield against sunlight. It is best if young dogs with lightly pigmented noses, as a preventative, are tattooed before any lesions develop.

Color mutant alopecia is a condition of the coat associated with blue (dilute black) or fawn (dilute brown) coat colors. It affects blue, and occasionally red, Doberman Pinschers. Despite the name, other breeds can have a hair loss linked to coat color. Most notable are blue Chow Chows, Dachshunds, Whippets, Standard Poodles and Great Danes. Most dogs who develop this condition are born with (except for color) normal appearing coats. Symptoms generally develop in dogs 4 months to 3 years of age. As they grow and mature, they develop brittle hair, followed by patchy hair loss sometimes referred to as a 'moth-eaten' coat. Only the blue portions of the coat are affected. Other colored areas remain normal. Secondary infection and inflammation of the hair follicles is also seen.

Initially, the dog will appear quite normal, but with a thin coat in the blue areas. As the condition advances, the skin also becomes involved and can become infected. The condition is incurable. Treatment, however, may help alleviate some of the symptoms. Medicated shampoos such as benzoyl peroxide may help reduce scaling and itching.

Sunburn

Cats and dogs can get sunburned. Cats with white ears are especially prone to develop sunburn on the tips and edges of the ears. Collies and other dog breeds such as Shetland Sheepdogs who have no pigment on their nose can develop a condition called 'Collie Nose' or 'nasal solar dermatitis'. This is actually caused by a hypersensitivity to the sun.

Some pets whose hair is clipped very short over their bodies or for some reason have sparse hair can also develop sunburn where their skin is exposed. Pets susceptible to sunburn should be kept out of direct summer sun, especially in the middle of the day when the sun is particularly strong.

Sunscreens (SPF should be 15 or greater), including those developed specifically for pets and those containing titanium dioxide or PABA as the active ingredient should be used to prevent sunburn. For pets with skin exposed on their bodies, a t-shirt (children's or adult, depending on the size of the pet) can be fitted over the body.

As with humans, animals with skin that has been sunburned are more likely to develop skin cancer, so protection from sunburn is extremely important.

There are several conditions which can cause a thickening of the skin at the elbow. The most common cause is callus formation. Calluses frequently occur in large, short-haired breeds of dogs that sleep on hard surfaces such as wood or concrete. To manage this condition, the sleeping areas of the dog should be changed. Soft bedding such as foam rubber padding should be used. Calluses can become infected, and conditions other than calluses can cause the skin changes you see on your dog. Therefore, it would be a good idea to have your veterinarian check any skin changes on your dog's elbows.

Histiocytoma

Histiocytomas can affect dogs of any age. They can appear on any location on the body, however, the vast majority of histiocytomas appear on the head. Histiocytomas usually occur on dogs under three years of age; histiocytomas are one of the most common tumors in this age group. The breed or sex of the dog does not appear to influence their development. These tumors appear rapidly and are small, round, and hairless. They will often ulcerate and then become smaller and go away. They usually appear as a solitary mass, but more than one may be present at a time. These tumors are benign and are not considered to be a health risk.

Treatment often involves just letting the tumor run its course. Histiocytomas can be surgically removed if they are bothering the dog and are in a location where the removal will allow for closure of the skin. They can also be treated with topical steroids and antibiotics if they ulcerate, become inflamed or infected. However, most dogs never receive nor require any treatment intervention. If you see a small tumor that develops on your dog make sure to have it examined by your veterinarian.

Description and cause

Also known as acute moist dermatitis, hot spots are usually a disease of dogs with long hair or those with dense undercoats. It is often caused by a local allergic reaction to a specific antigen. Insect bites, especially from fleas, are often found to be the cause.

Hot spots are circular lesions, usually found on the head, over the hip and along the side of the chest. They will be moist, raw, inflamed and hairless, and can be quite painful. Animals usually lick, bite or scratch the area, and thus irritate the inflamed skin even more. In fact, hot spots are sometimes called 'pyotraumatic dermatitis' because the self-trauma is a major factor in the development of hot spots.

Hot Spots can change dramatically in size in a very brief period of time. What was the size of a quarter may easily be eight inches in diameter in six hours. The lesions are rare in the colder temperatures of winter. They occur in equal frequency in both inside and outside dogs. Many dogs develop several of these lesions over the course of their lives. However, this is not a long-term disease. A lesion will suddenly appear, be treated and be gone in less than a week Another lesion will suddenly appear later the same summer, the next year or never be seen again on that dog.

Treatment

Treatment must be directed at stopping the growth of the hot spot and eliminating the cause. In many dogs the initial cause is fleas, but lesions below the ear often indicate an ear infection, those near the hip may be the result of an anal gland infection, and so on. Whatever the cause, if it can be detected, it must be treated while the hot spot is being treated.

The first step in treating hot spots is clipping the hair over and surrounding the lesion. This allows air to get into the inflamed tissue and makes it easier to treat. The surface of the lesion is then cleaned with a non-irritating solution such as dilute Nolvasan solution. To help the lesion heal desiccating powders such as Burows solution (Domeboro powder and water) are often then applied. If the dog is very sensitive this may need to be done under sedation. In more severe cases the animal may be placed on oral antibiotics and given painkillers and anti-inflammatories such as buffered aspirin or steroids. (Do NOT give your cat aspirin unless prescribed by your veterinarian.) We also need to prevent the dog from traumatizing the area even more. Elizabethan collars (those plastic 'satellite dishes') may be used if the lesion is on the top of the head, for instance. Nails can be clipped and socks can be put on the hind feet to reduce trauma from possible scratching.

Prevention

Many dogs that have repeated problems with hot spots can have the incidence greatly reduced by keeping their hair clipped short during summer, giving them frequent medicated baths and following a strict flea control program. Depending on the location of the hot spot, cleaning the ears regularly and expressing the anal glands as needed may also be beneficial.

Warts, also called 'cutaneous papillomas', occur most commonly in young dogs. Many are thought to result from an infection with a certain virus called pavavirus (not parvovirus). They usually occur on the dog's face including the lips, tongue, inside of the mouth, and eyelids. The warts are generally light colored and have a cauliflower-like appearance.

Warts caused by viruses are usually benign and will generally go away by themselves in several weeks or months. Therefore treatment is generally withheld. If, however, the warts are interfering with eating or become very large, they can be removed. Generally, cryosurgery (freezing the tissue) is the method of choice.

Puppy Impetigo (Puppy Pyoderma, Juvenile Pustular Dermatitis)

This skin infection is usually seen in puppies less than one year of age. The areas most often involved are the chin and/or abdomen. Staphylococcus bacteria are usually present and thought to be a main cause of puppy impetigo. In the dog, impetigo is used to describe small areas of infection found on the hairless area of the abdomen (belly). Small areas filled with pus (pustules) can be seen. Often these pustules break and form crusts or circular areas of scaling skin. Impetigo in puppies seldom creates more than a localized area of infection. It is not life threatening and some mild cases may resolve on their own. Rarely, the infection can spread and become deeper.

To treat the condition, Hydrogen peroxide, chlorhexidine or benzoyl peroxide applied twice daily will usually clear the condition. Excellent benzoyl peroxide shampoos are available to treat this condition. In severe cases your veterinarian may prescribe antibiotics, to be given orally or topically. Most puppies outgrow the condition. In Doberman Pinschers, Bulldogs, Boxers and Chinese Shar Peis, impetigo may persist into adulthood.

Schnauzer Comedo Syndrome (Schnauzer Back)

Although other breeds may be involved, this condition is typically seen in Miniature Schnauzers, suggesting a genetic predisposition. Generally the area along the spine is the most affected. Raised, black, crusty bumps will develop all along the back area. These may reach the size of up to one inch in diameter. Patchy hair loss will be evident and the skin may become thickened and red. In some dogs, the skin takes on an oily nature with a strong odor. While not life threatening, this condition affects the appearance and smell of the animal.

Treatment is aimed at managing the condition. Comedo syndrome usually persists in varying degrees for the life of the pet. Medicated shampoos such as benzoyl peroxide work well and should be used on a regular basis, often at least weekly. If a secondary bacterial infection develops, antibiotics may be given. Although not usually curable, the condition can be successfully managed.

If your pet has flaky, dry, or greasy skin and haircoat, he may have a condition called seborrhea. Seborrhea, in humans or animals, is caused by an abnormal 'gearing up' of certain cells in the skin, including cells of the sebaceous (oil) glands and the basic skin cells.

In seborrhea, the sebaceous glands (found in or near hair follicles, whose normal function is to enrich the skin with oil secretions) increase the amount and quantity of their secretions.

An abnormal turnover of the skin cells (keratinocytes) into dead scale (keratin) also occurs. Normally the cells in the skin are constantly dying and being worn off; new cells to replace them from deeper in the skin. So there is a constant migration of deeper cells moving to the surface, undergoing keratinization (making keratin and dying), and being sloughed off. This migration usually takes 3 weeks. This cycle is changed in animals with seborrhea. The migration is greatly accelerated and only takes several days. Thus there is a buildup of this keratin on the surface of the skin. This is why seborrhea is commonly termed a 'keratinization disorder'.

Seborrhea can be broken down into two groups, based upon the cause. Primary seborrhea can be either genetic-based or caused by a keratinization disorder. Secondary seborrhea is a result of other disease processes such as allergies, parasites, nutritional disorders, and endocrine (hormonal) disorders such as hypothyroidism. To determine the best treatment, it is important to differentiate whether a dog has primary or secondary seborrhea. Dogs with secondary seborrhea must be treated for its cause, such as allergies or zinc deficiency.

Seborrhea is characterized by skin that is excessively flaky, and can be divided into several types depending upon the signs and symptoms. The two most commonly referred to are:

Seborrhea sicca, or dry seborrhea which shows dry scaliness only. This type is common among Irish Setters and Doberman Pinschers.

Seborrhea oleosa, or oily seborrhea, in which the scales are accompanied by an oily coat. This type is common among Cocker Spaniels and West Highland White Terriers.

In addition to flakiness, dogs with seborrhea often have an increased odor and may tend to scratch and lick various parts of their body.

Symptomatic treatments may include clipping or shaving the haircoat which will make shampooing much more effective since we need to get the shampoo down to the skin. Frequent shampooing with special medicated shampoos selected according to the type of seborrhea present (sicca or oleosa) are very important. In some cases, special rinses or ointments to flush out the hair follicles may be used. Essential fatty acid supplements are often given. This may seem counterintuitive since the coat may already be 'greasy', however the fatty acids are essential for normal skin cell function and will help the condition, not exacerbate it. In cases of secondary seborrhea, the underlying cause should be diagnosed and appropriate treatment given as directed by your veterinarian.